The present invention relates to an allergy test chamber having at least one inlet for supplying allergen-free air, especially fresh air, into the chamber.
The effectiveness of anti-allergy treatment can only be evaluated objectively if allergic subjects are monitored under the natural load of a specific allergen, as for instance grass pollen. The potential use of data which have been obtained within the framework of such a clinical study carried out under environmental conditions is severely restricted by the extreme fluctuation of allergen concentration in the air. Not only does it vary from one region to the other, as shown in FIG. 1 by way of the concentration of grass pollen in Europe on Jun. 10, 2000, the dark areas indicating high concentration levels and the light areas representing low pollen concentration, from one year to the next and within one season (see FIG. 2, showing seasonal variations and the average grass pollen count of 20 years), but also within one day and quite substantially with the distance from ground level. In addition, patients' reactions to allergens in the air vary considerably in the course of one season because of a priming effect and other less important phenomena. These problems are brought to light more clearly with subjectively tolerable symptoms, like conjunctivitis, less clearly with rhinitis and rarely ever with severe attacks, like asthma.
Another problem is the consistent registration over a period of several days, as it can almost only be achieved by a subjective evaluation of symptoms. The reliability of documentation in diaries kept by patients declines with every day of the study. In order to obtain statistical material that can be used in studies for doses finding, effectiveness or duration of effect, a large number of patients and long periods of observation are necessary. However, a low amount of pollen and many other environmental factors may lead to unexpectedly insignificant results in field studies.
Therefore it is necessary to find a solution for clinical experiments with patients suffering from allergies to pollen and house-dust mites which come close to field studies without having their disadvantages.
At present tests carried out in allergy test chambers are undisputedly known as “Golden Standard” by means of which the above problems can be overcome (Cartier A., et al., “Guidelines for bronchoprovocation on the investigation of occupational asthma”, Report of the Subcommittee on Provocation for Occupational Asthma. J Allergy Clin Immunol 1989, 84:823-829); Melillo G., “European Academy of Allergy and Clinical Immunology—Provocation tests with allergens”, Allergy 1997, Suppl. 35, 52:1-35). These chambers make it possible to carry out tests by inhaling allergens under controlled conditions coming close to natural load and furthermore guaranteeing precise and comprehensive results for every patient. As an allergen test chamber enables exact studies while generating a large number of numerical data, they make it possible for the researcher to obtain statistically significant results with a by far lower number of patients than would be required in a field study.
The so far most sophisticated allergy test chamber comprises a room sealable with respect to external air wherein a number of fans are disposed, which circulate the air horizontally within the room. Allergens, e.g. grass pollen or mite faeces, are introduced into the air within the room by putting up one or several cups containing a predetermined amount of allergens in front of respective fans and swirling them by the draft caused by the fan. It is attempted to remedy the relatively unequal distribution of allergens within the room thus achieved by instructing the test subjects to change their positions within the room at regular time intervals.
It would be desirable to have an allergy test chamber guaranteeing a considerably improved uniformity of allergen load of the air within the room thus further improving objectivization and reproducibility of test with test subjects.